Contained herein is material that is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction of the patent disclosure by any person as it appears in the Patent and Trademark Office patent files or records, but otherwise reserves all rights to the copyright whatsoever.
The present invention relates to the field of personal digital assistants; more particularly, the present invention relates to a personal digital assistant having a power management mechanism.
The popularity and use of Personal Digital Assistants (PDAs) has increased in recent years. A PDA or hand-held computer is primarily a lightweight, compact productivity and communications tool that can typically be held in one hand, leaving the other hand free to input data with a pen type stylus or a reduced size keyboard.
A PDA provides computing and information storage and retrieval capabilities for personal or business use. Typical uses include schedule and address book storage and retrieval, as well as note taking functions. In addition, many PDAs are capable of running a variety of application software packages (e.g., calculators, text and/or image editors, etc.). Moreover, many existing PDAs offer the ability to wirelessly transmit and receive electronic-mail (e-mail) messages, calendar events, contact lists, etc.
The problems of power consumption in PDAs has become of greater concern as ever-greater computing power is housed in ever-smaller PDA enclosures. In battery-powered computers (e.g., a PDA, pager, etc.), power conservation is required to increase battery life and thereby increase the period of time that the PDA can be used prior to recharging or replacing the batteries.
One power conservation method for PDAs is to use a belt clip with a magnet attached to the clip. The PDA includes a Reed switch that is located so that it will sense the magnet whenever the PDA is placed into the clip. Once the PDA is placed into the clip, the Reed switch detects the magnet. As a result, the PDA enters a sleep mode wherein power is conserved.
The problem is that if the user does not have a clip, there is no way to conserve power without completely turning off the PDA. For example, a user may have a PDA in a bag or purse, without turning the power off. While the PDA is in the bag, power is being wasted since there is no intention by the user of the PDA being immediately used. Therefore, a PDA with improved power management is desired.
According to one embodiment, a handheld device is disclosed. The handheld device includes a housing, a display mounted within the housing, a light sensor mounted with an LED under a light pipe, and a light sensor mounted within the housing to detect light beams though the display. In one embodiment, the light sensor is coupled to a power management unit that causes the handheld device to go into a sleep state whenever no light beams are detected at the light sensor. In a further embodiment, the handheld device includes an electro luminescent (EL) sheet mounted within the housing that provides lighting for the display and the keypads. In yet a further embodiment, the EL sheet is automatically activated whenever the handheld device is being operated in a dark environment.